Effect of spikelet removal on the whole plant senescence of rice

Abstract

The rice (Oryza sativa L.) cultivar IET 1444 showed a nonsequential mode of senescence as evident from the decline in chlorophyll and protein of the flag and second leaves at the senescent stage. Removal of 50, 75 and 100 % spikelets from the panicle of rice plant or emasculation of the panicle by hot water treatment induced the development of secondary branch from the axil of second leaf but 25 % removal had no effect. Similarly, removal of 75 and 100 per cent spikelets from the panicle of secondary branch induced tertiary branch development, while 25 and 50 per cent removal had no such effect. Similar treatments on tertiary branch had no effect on further branch production. The pattern of leaf senescence of the untreated (control) main tiller, secondary and tertiary branches was identical, i. e. nonsequential, which could be changed into the sequential type only by the development of additional sinks (i. e. side branch). The leaf area and the seed number of secondary and tertiary branches were gradually reduced and reached a critical value in the tertiary branch. The removal of spikelets or emasculation delayed leaf senescence of the main tiller and the secondary and tertiary branches. Also the longevity of the whole plant could be increased by 40 d i. e., up to the senescence of the tertiary branch. Both leaves and reproductive parts control side branch production, which, in turn, controls the longevity of the whole rice plant.

Photosynthesis and Dry-Matter Production during Ripening Stage in a Female-Sterile Line of Rice

“…Panicle removal had no effect on the photosynthetic ability of the fl ag leaf (Cho et al, 1981) and retarded the decrease of photosynthetic ability in the fl ag leaf during plant senescence . Spikelet removal or emasculation delayed leaf senescence of the main, secondary, and tertiary branches in rice (Khan and Choudhuri, 1991). In rice, however, the panicle photosynthesis is not negligible (Ishihara et al, 1990) and panicle removal reduced light interception and increased net canopy photosynthesis after fl owering (Setter et al, 1995).…”

Effects of early-fruit removal on endogenous cytokinins and abscisic acid in relation to leaf senescence in cotton

“…Loss of early fruiting forms has also been shown to increase root growth (Sadras 1996;Dumka et al 2004), alter spatial yield distribution (Bednarz and Roberts 2001), and improve Cry1AC expression of transgenic Bacillus thuringiensis Berliner (Bt) cotton (Zhang et al 2008). Removal of flowers or physical restriction of pod growth delayed leaf senescence in soybean (Noodèn 1988;Miceli et al 1995) and rice (Khan and Choudhuri 1991). However, few studies have examined changes in leaf senescence following early-fruit removal in cotton.…”